Test fabrication of JOYO fuel, (6)

Claddings should be used for fuel pin fabrication after many kinds of inspections to meet with specified requirements. The inspection is limited to dimensional one, and other inspection processes such as destructive one and others were not adopted, considering fabrication economy, though those processes seem more preferable. As it is not known which specification is critical for the assurance of the integrity of fuel claddings, the characteristics of claddings must be examined as precisely as possible before irradiation. The elastic property, plastic property and burst strength of the weld part of cladding tubes were obtained in this work. Elastic constant (Young's Modulus E) was determined by the measurement of the deflection of a cladding as a cantilever with the aid of beam theory. Plastic property was determined from stress-strain curves with the equation sigma=c(a+epsilonsub(p))sup(n). Burst test of the welded part of cladding tubes was carried out with the concentrated internal pressure at the welded part. The burst strength of end plug part is about 240 kg higher than that of cladding itself. The results obtained were tabulated in the report. The other required characteristics of claddings for fuel pin fabrication to be specified are oxidized layer, grain size, electric resistance and melting point. (Iwase, T.)